In recent years, there has been an increase in the demand for an increase in data communication speed and low power consumption circuitry between electronic devices. Using low-voltage transistors, which are advantageous for their switching speed and power consumption characteristics, in data communications circuitry disposed between electronic devices is effective in meeting this demand.
For example, a differential output circuit used as an output buffer for, for example, the High-Definition Multimedia Interface (R) (HDMI), is an open drain circuit, and has a configuration in which a termination voltage of 3.3V is applied from an external source. When low-voltage transistors are applied to differential output circuits that conventionally use high-voltage transistors, problems arise with overvoltage reliability.
Patent Literature (PTL) 1 discloses a data communications circuit having a configuration in which cascode transistors are connected to differential input pair transistor drains. The drain voltage from one of the cascode transistors is supplied to the gate of the other cascode transistor. This cascode transistor connection configuration reduces the potential difference between the terminals of each transistor. This makes it possible to increase durability with respect to overvoltage, even when low-voltage transistors are used in a data communications circuit of which high-voltage is demanded. Moreover, since the bias voltage that is supplied to the gate of a cascode transistor is supplied from an output terminal, an appropriate bias voltage is supplied even if the voltage in the differential output circuit is lower than the output terminal voltage, and the low-voltage transistors are protected from overvoltage.